Fluid pressure device



Sept 16, 1941. c. M. KENDRICK FLUID PRESSURE DEVICE 4 sheets-sheet 1 km QN, u

Filed Feb. l2, 1941 Sept 15, l941- C. M. KENDRICK l 2,256,459 FLUID PRESSURE DEVICE Filed Feb. l2, 1941 4 Sheets-Sheet 2 INVENTOE Charles M. Kendrick RNEYS SePt- 16, l941- C. M. KENDRICK 2,256,459

FLUID PRESSURE DEVICE Filed Feb. l2, 1941 4 Sheets-Sheet 5 lNVENTOR Ch les M. endrck MKM/wf, @EMU ATTO NEYS Sept. 16, 1941. c. M. KENDRICK I FLUID PRESSURE DEVICE 4 Smets-sheet 4 Filed Feb. l2, 1941 W 6J Z Z k uw ma. fwn Re mK m mMcwm mm ,A In m CV..

Patented Sept. 16, 1941 UNITED sTATEs PATENT oFFlcE FLUm PRESSURE DEVICE Charles M. Kendrick, New York, N. Y., assignor to Manly Corporation, Washington, D. C., a corporation of Delaware Application February 12, 1941, Serial No. 378,524

15 claims. (ci. 10a-136) This'lnvention relates to iiuid pressure devices and more particularly to devices of this character employed as pumps capable of delivering two separate uid volumes at the same or different pressures, althoughsome features of the invention are likewise applicable to uid pressure devices employed as uid motors, as will be more particularly explained hereinafter. The present application is a continuation in part of co-pending application filed May 5, 1939, Serial No. 271,874. n

Fluid pressure devices of the character under consideration find their widest present use as hydraulic pumps or motors, that is to say, as pumps for handling or motors whose motive uid is a liquid, such, for example, as o il. The present invention will accordingly be described in connection with a pump for such use, although it will be understood that the invention is also appli cable to pumps operating with elastic fluids and that some features of the invention are also Y applicable to fluid motors, as already stated.

One important use for a` pump of the character under consideration is as the source of pressure fluid in a fluid power system in which it is necessary or desirable to employ operating pressure fluids having different but related pressures. This is the case, for example. when the fluid system includes a fluid motor of the vane type in which the vanes move inward and outward of the rotor in a substantially radial direction. In vane motors of this character it is often necessary to force the vanes radially outward during certain portions of their rotary travel, particularly at starting and when the motor is operating at low rotative speeds, so that the outer ends of the vanes will be held flrmly in contact with the surrounding vane track and thus provide a movable resistance to the pressure fluid admitted to the pressure areas at the outer ends of the vanes of the fluid motor, whereby rotary motion is imparted to the rotor and the driven shaft of the vane motor.

'A highly practical and satisfactory method for forcing the vanes of the motor radially outward against the vane track is by introducing or admitting, behind the inner ends of the vanes, pressure fluid having a pressure greater than but related to the pressure of the fluid admitted to the pressure areas at the outer ends of said vanes, as fully explained in my co-pending application led March 28, 1938, Serial Number 198,449. Thus fluid under two different but related operating pressures is used; the fluid having the higher of these two pressures, which for convenience .is termed the diierential high pressure duid," is admitted to the radially inner ends of the vanes, while iluid under the lesser of these two pressures is admitted to the pressure areas at the outer ends of the vanes of the vane motor.

An object of the present invention is to provide a simple and improved fluid pressure .device of the character indicated.

Another-object is to provide a pump capable `of delivering two iiuid volumes at different pressures for use. for example,in the above-men-` tioned uid powerl system or for any other suitable purpose.

Another object is to provide a pump of this character in which both of the two fluid volumes may be simultaneously and conformably varied. A further object is to provide a pump of this character capable of delivering twouid volumes ofthe same or dlierent circulateduids at the same or different pressures.

A still further and more specific lobject is to provide a simple, rotary vane type pump of this character.

Otherv and more specic objects will appear from the description which follows. Y

The invention will be understood from consideration of the -accompanying drawings which illustrate, by way of example, embodiments of the present invention.

In the drawings:

Fig. 1 is a view. partly diagrammatic and partly in section, showing a rotary piston element pump according to the present invention which serves as a source of pressure uid in a fluid power system that includes a vane type fluid motor; Fig. 1 includesa longitudinal view of the pump taken along the line I-I of Fig. 2

, and also includes a corresponding longitudinal thereof adjacent the rotor;

Fig. 3 is a view of the vane type motor unit. in vertical transverse section, taken along the line 3-3 of Fig. 1;

Fig. 3a is a view ofv one of the end plate elements of the motor unit showing the face thereof adjacent the rotor Fig. 4 is a view of a modified end plateelement for the pump unit, also showing the face thereof adjacent the rotor;

Fig. 5 is a diagrammatic view, partly in section, showing a modification.

Figs. 1, 2, 2a, 2b, 3 and 3a are also shown in co-pending application filed May 5, 1939, Serial Number 271,874, in which certain parts of the subject matter thereof are claimed.

Referring now to these drawings, in Figs. 1 to 3a inclusive I have illustrated the present invention as embodied in a rotary piston element pump, here shown as a vane type pump A forming part of a iiuid power system which includes a vane type fluid motor B. The pump A and the motor B may both be o f fixed stroke or capacity per revolution or both of them may be of variable stroke, or one may be of variable stroke and the other of fixed stroke. In the embodiment illustrated in the drawings above mentioned I have shown the pump A as of variable stroke and the motor B as of ilxed stroke, as will be hereinafter more fully explained.

In the particular embodiment of pump structure shown the pump casing is in two axially separate parts I and II (Fig. 1) which are suitably fastened together as by cap screws, not shown, and which cooperate to form a cavity for the rotor AI and associated parts. The rotor I5 is rotatably supported` by its hubs Ii which extend into bushings Il carried by the casing parts IIi and II respectively and said rotor also has a slidable splined connection with the driving shaft 20 (Figs. 1 and 2) which passes through the bore of said rotor and is revolubly supported by a pair of bearings 2|. A pair of mating end plates 23 and 24 are disposed on opposite sides of the rotor and between the spacer ring I4 and the casing parts, the arrangement being such that the rotor turns freely while its sides and the sides of the vanes I! form substantially fluid-tight running fits with the adjacent faces of said end plates. The end plates 23 and 24 are provided with holes at their cen- .ters through which pass the rotor hubs I6, and

are also provided with ports and fluid passages to be later described.

-As best shown in Fig. 2 the pump A is a rotary piston multi-section or part pump consisting of two pumping sections or halves which are separated from each other by fixed abutments 3l and which discharge into a common discharge channel 45, to be presently described. The rotor I5 is provided with a multiplicity of vane slots Il in each of which is a vane I! adapted to move radially inward and outward therein as the rotor revolves. The radially outward ends of the vane I9 follow a trackway that controls their inward and outward movement and which comprises the two fixed abutments 3l, two movable abutments 3| and connecting flexible track elements 34. 'I'he track surfaces on the inner -ends of the fixed abutments I0 are preferably spaced a slight amount from the periphery of the rotor to provide a clearance therebetween which forms a sealing chamber that separates the high and low pressure areas on the opposite circumferential sides thereof, with separation being effected by the rotor and vanes in cooperation with the track surfaces on the iixed abutments 30. The movable abutments are slid- `ably spported in slideways 33 formed in the spacer ring I4 on the interior of the casing and are adapted to be radially adjusted with respect to the circumferential rotor surface. The work of pumping by the exposed outer ends of the vane I 9 is done as the vanes move across an arc 32 on each movable abutment, termed the "working or pumping arc, the fluid being received at one end of this arc and discharged at the other. Regulation of the stroke or volumetric capacity per revolution of the pump is effected by moving or radially adjusting the movable abutments 3i to vary the distance separating the pumping arcs l2 from the circumferential rotor surface; the flexible track elements 34 have extensible connections with the fixed abutments 3l thereby permitting adjustment of the movable abutments 3i without change of position of said fixed abutments 3l.

The movable abutments 3| are adapted to be moved by means of a pair of adjusting rods 3l which are attached thereto as by the pivot pins 36. The adjusting rods extend through suitable holes in the spacer ring I4 and in the side covers I2 which close the horizontal adjusting rod bores formed in the casing part I0. Movement or adjustment of the adjusting rods 35 and movable abutments Il maybe effected by any suitable means, not shown, which lmay be conveniently connected with the links .31 on the outer ends of the adjusting rods. It will be understood that the volume of fluid pumped by the outer ends of the vanes of each pumping section is dependent upon the distance between the circumferential surface of the rotor I5 and the pumping arc 32 of the corresponding movable abutment 3| so that the output of each half of the pumping section may be infinitely varied at will. It will also be understood that the total volume of fluid pumped by the outer ends of the vanes comprises the combined volumes pumped thereby as the vanes pass across the pumping arcs of'the two pumping sections. The particular structure admission and discharge to and from the outer ends of the vanes I9 is accomplished through ports in the end plate 23, these ports comprising a pair of diametrically opposite arcuate inlet ports 2i and a similar pair of outlet ports 2l as shown in Fig. 2a. The outlet ports 26 of the end plate 2l are also shown inthe sectional view of Fig. 1. 'I'he end plate 24 (Fig. 2b) is likewise provided with similar ports 25 and 2l (here shown in Figs. 1 and 2b as recessed and not extending through the end plate 24) which serve principally as balance ports to contain fluid under the same pressure as that in the corresponding ports in the end plate 23 in order to substantially balance the hydraulic forces acting on the sides or axial ends of the vanes to prevent binding thereof.

Each outlet port 28 of the end plate 23 registers with a similar port formed in the side walls of `the casing member I Ii which is connected by a slanted passage 3l with the outlet conduit 45 as shown in Fig. 1. The outlet conduit 4l is -pumping sections of the pump.

by the reference I ends of the vanes as indicated by the dotted lines at 40 in Fig. 1, with a passage 39 leading to the vane motor B. The inlet ports 25 o! the end plate 23 are similarly connected with the lnlet conduit 43 or they may be connected therewith in any other suitable manner, and the conduit 43 is connected with the uid supply pipe 42, as indicated by the dotted lines at 4I in Fig. l, which may be connected with a suitable reservoir, not shown.

When therotor I5 revolves in a counter-clockwise direction, as viewed in Fig. 2, fluid enters through the inlet ports 25 of the end plate 23 and passes between the outer ends of `those vanes I9 that are in the inlet area of each of the two 'Pumping is accomplished by the rotary motion of the outer ends of the vanes I9 as they sweep across the pumping arcs 32, said vanes I3 thus forcing uid into the outlet area of each of. the two pumping sections from which it passes out through the outlet ports 26 of the end plate 23 and into the discharge channel'45. As already stated, the size of the pumping chambers and the volume of iiuid delivered by the pump are determined by the distance of the pumping arcs 32 from the rotor I5; as this distance may be varied in infinitely small increments from minimum to maximum, the size of the pumping chambers, and hence the volume of fluid pumped by the outer ends of the vanes, may likewise be varied from minimum to maximum.

The structure of the motor B' (Fig. 1) is identical with that as already described in connection with the pump A except in certain parts to be presently explained. For convenience in distinguishing between pump and motor parts suitably connected,

ports and that the discharge ports 26' are its low pressure ports whereas the reverse relative pressure condition exists in the inlet ports and outlet ports 26Aof the pump A.

The inlet ports 25' in the end plate 23' of the motor B are connected with the motors inlet chanel 43' by means of registering ports in the side walls of the casing member I0' and slanted passages 38', as plainly shown in Fig. 1 wherein a sectional view through the ports 25' isl illustrated. The inlet channel 43' of the motor B is connected with the passage 39 leading from the pump A as indicated by the dotted linesl 4B' of Fig. 1. The discharge ports 26' of the end plate 23 are connected in a similar manner, not shown, with the discharge channel 45 which in turn is connected with the return passage 46, as indicated by the dotted lines at l4I', which leads to the reservo' not shown. In this connection it may be pointed out that the iiuid passages between the outlet channels of the in the explanation which follows, the parts of the` motor which are identical with those of the pump have been designated by the same reference numeral by adding prime as for example the rotor of the pump ence numeral I5 and the -rotor of the motor B numeral I5', etc. j

The motor B, as here illustrated, is also a rotary piston multi-section or part device as best shown in Fig. 3, but as already stated is of fixed stroke or capacity per. revolution. It is accordingly provided with a non-adjustable vane track comprising a vane track ring I4' having an interior vane-contacting track or surface. The vane track surface may be given any suitable contour but is preferably provided with concentric arcs 30' at its regions of least diameter and concentric working arcs or chambers 32 at its regions of greatest diameter, the arcs 30' and 32' being joined by intermediate connecting portions 34 of any suitable curvature producing satisfactory rates of inward and outward movement of the vanes I9' as the rotor I5' revolves.

Pressure uid is admitted to the exposedouter I9' as they approach the working arcs 32 and acts against the exposed outer ends of said vanes as they move across said working arcs, thus imparting rotary motion to the rotor I5 and the driven shaft 20'-.\141luid is discharged from the outer ends of the vanes I9 as they recede from the working arcs 32'. All admission and exhaust to and from the outer ends of the vanes I3 is accomplished through inlet and outlet ports in the end plate` 23 identical in arrangement with the already described ports of the pumps end plate 23 as will be evident from Fig. 3a, but it will be noted that the ports 25 of the motor B are the high pressure A is designated by the refer-` motor B and the corresponding` ports 26' in the end plate 23' are identical withthe corresponding outlet passages of the pump A; the sectional view of the motor B is taken through. its inlet areas whereas the sectional View of the pump A is taken through its outlet areas so that the exact arrangement of all ports and passages may be readily understood therefrom, although it will be understood that these exact arrangements are not` necessary and may be variedv if desired. The end plate 24' is also provided with recessed inlet ports 25 and outlet ports 26', similar to the ports in the pump end plate 24;.these ports in the end plate 24 serve principally as fbalance ports. as all fluid is admitted to and exhausted from the outer ends of the vanes I9' through the ports of the end plate 23. as already stated. `The particular structure of the vane track ring I4', rotor I5 and plates 23 and 24', etc., forms no part of the present application but a part of application Serial Number 198,449, led March 28, 1938, and it will` be understood that any other suitable structure may be ern'- ployed.'

With the parts of the motor B in the position illustrated in Fig. 3 and with the pump A in operation and adjusted so that fluid is being pumped by the outer ends of its vanes I9, pressure fluid from the pump-A will enterthe inlet ports 25 of the motor B and rotate the rotor I5' and driven shaft 20' in a clockwise direction as viewed in Fig. 3. The speed of rotation of the rotor i5J of the motor B is determined by the volume of fluid admitted to the outer ends of its vanes I9 which in turn is determined by V'the volume of fluid delivered thereto by the pump A; the speed of rotation of the rotor I5' of the motor B may` thus be infinitely varied from minimum to maximum by corresponding variation in the output of the pump A. In order for operation to take place however, it is necessary that the vanes I9' be iirmly in contact with.. the vane track surface at the working arcs 32* and that there be similar contact between the ends of the vanes I9' .and the vane track at the arcs( 30.' to thereby separate 4the two fluid sections of the motor B. This contact between the vanes I9 and the vane track is accomplished by introducing behind the radially inner `ends of said vanes I 9 fluid having a pressure greater than but correlated with the pressure of the iiuid admitted to the inlet ports 25'.' The means'by.

which this higher pressure fluid (for convenience hereafter termed diii'erential high pressure 2-1 and 28 are positioned tol register successively with the inner ends of the vane slots I8 as the rotor I5 revolves and they act as ports or passages for fluid to and from said vane slots I8 and hence are termed vane slot ports.

The vane slot ports 21 are connected with the inlet ports 25 by radial passages or grooves 29 on the outer faces of the end plates 23 and 24 and the length of said vane slot ports 21 is such that the inner ends of each vane slot I8 connects therewith during the time that the outer end of its corresponding vane I8 is moving across the flexible interconnecting track element 34 that lies in each of the inlet areas of the pump A; the inner end of each vane slot I8 is thus connected with the fluid inlet supply during the time that its corresponding vane I8 ismoving through the inlet areas of the pump A and is approaching the pumping arcs 32.. 'I'he inner end of each vane slot I8 is thus filled with fluid as its corresponding vane I9 moves radially outward under the action of centrifugal force while said vane I8 is passing from each flxed abutment 30 toward the contiguous pumping arc 32..

Fluid entering the inner ends of the vane slots I8 through the vane slot ports 21 as explained above is discharged into the vane slotl ports 28 as the outer end of each vane I9 moves inward during the time it is passing from the pumping arc 32 of each pumping section through the corresponding outlet area of the pump and on to the contiguous fixed abutment 38. Thiswill be understood by referring to Fig. 2 in which it will be observed that the vanes I9 occupy the extreme radially outward position when their outer ends are in contact with the pumping arcs 32; it will also be observed that said vanes I9 are moved progressively inward as said vanes traverse the interconnecting track element 34 intermediate said pumping arc 32 and the contiguous fixed abutment 30; and it will further be observed that the vanes I8 occupy the extreme radially inward position when their outer ends are in contact with the fixed abutments 30. It will thus be seen that each vane I9 functions as a piston reciprocating in its vane slot I8, the inner end of which serves as a cylinder therefor, and it will also be seen that each vane I8 is reciprocated twice for each revolution of the rotor I5. It will further be seen that admission of fluid to the inner ends of the vane slots I8 takes place simultaneously with admission of uid to the outer end of the corresponding vanes I9 and that uid is likewise discharged from both the inner and the outer ends of the vanes as said vanes recede from the pumping arcs 32 and approach Athe fixed abutments 30. 'Ihe vane slot ports 28 in this embodiment are made of such length that they also connect with the inner ends of those vane slots I8 whose vanes I9 are in contact with the pumping arcs 32 and the fixed abutments 30 so that fluid pressure is applied to the inner ends of such vanes to assist in holding their outer ends rmly in contact with the vane track surfaces as said vanes move across the xed and movable abutments.

'I'he volume of iluid of the vanes I8, per revolution of the rotor I l, for any particular rotor and vane assembly is dependent upon and varies conformably with thevstroke of the vanes which, as already explained, is determined by the distance between the pumping arcs 32 and the circumferential rotor surface and may be infinitely varied at will. "I'he volume of fluid pumped by the inner ends of the vanes may thus be infinitely varied from minimum to maximum and variation in the volume pumped by the inner ends of the vanes is eifected simultaneously and conformably with variation in the uid volume pumped by the outer ends of said vanes as they move across the pumping arcs. l

Fluid pumped by the inner ends of the vanes I8 of the pump A is utilized to provide the diffenential high pressure fluid to force the vanes I8 of the motor B radially outward against the passages providing this interconnection include va hole 22 in each of the vane slot ports 28 in the pumps end plate 24 and said hole 22 registers with a passage 41 leading to a channel 48 formed in the pump casing member II. The channel 48 is connected as by a pipe 49 with a corresponding channel 48' in the motor casing member II' and said channel 48' is connected through a passage 41l by a hole 22' with each vane slot port 21' in the motors end plate 24'.

At this pointit should be noted that the end plates 23' and 24 ofthe motor B are provided with vane slot ports 21 and 28' corresponding generally to the already described vane slot ports of -the-pumps end plates. The vane slot ports of the motors end plates 23 and 24 differ from those of the pumps end plates, however, in that the vane slot ports 21 (which in this instance are its high pressure vane slot ports) are not only co-extensive with the inlet ports 25 but in this embodiment are of such length that each vane slot I8 connects, therewith during the time that the vane I9 therein is traversing the arc 8l and the working arc 32 of each uid section as .well as while traversing the intermediate portion 84' of the track that lies in the inlet area of each fluid section of the motor B. Fluid entering the inner ends of the vane slots I 8 oi' the rotor I5' is discharged into the vane slot ports 28' which are connected with the outlet ports 26' of the end plates 23 and 24 by radial passages 28' on the outer faces thereof.

In order to assure that the vanes I8' of the motor B are forced radially outward against the vane track itis necessary that the volume of fluid pumped by the inner ends of the vanes I8 of the pump A beA equal to or greater than the actual fluid volume required to produce such radially outward movement o f the varies motor B. That is to say, the volume of the iluid pumped per revolution of the rotor I5 of the pump A by the inner ends of its vanes I8, at any stroke or capacity of the pump A, must have a relation to thev corresponding volume of the iluid pumped by the outer ends of said variesl I 8 that is equal to or greater than the relation of the uid volume required for the inner ends of the motors vanes I8' per revolution of its rotor I5' with respect to the fluid volume that must be admitted to the outer ends of the motors vanes I8' in order to produce one revolution of the ropumped by the inner ends tor I'. This relation will vary with particular embodiments and is due in part, for instance, to the porting provided for the inner 'end of the vane slots I8 of the motor B.

With the arrangement illustrated in Figs.. 1, 2, 2a, 2b, 3 and 3a, the flow of fluid with respect to the inner ends of the vanes of the pump and motor is as follows: Upon rotation of the pump rotor I5 .in a counter-clockwise direction, fluid will flow from the supply pipe 42 into the inlet conduit 43, and to the inlet ports 25 of the pumps end plate 23, and will fill the spaces between the outer ends of the vanes I9 as they pass through the pumps inlet areas. Fluid also passes from the ports 25 of both end plates 23 and 24, through the radial passages 29 onl the outer faces of said end plates, to the vane slot ports 21 of both end plates and into the inner ends of the vane slots I8. As the vanes I9 are moved inwardly While passing across the interconnecting track elements 34 in the outlet areas of the pump, fluid is pumped by the inner ends of said vanes I9 into the vane slot ports 28 of the end plate 24,

through Vthe holes or ports 22 in said end plate 24, into the passages 4'I, the channel 48, the pipe 49 and into the channel 46'` of the motor B; thence through the passages 41', holes or ports 22' of the end plate 24', vane slot ports 21 of the end plate 24' and thence below the inner ends of the vanes I9' to force them outwardly and into contact with the vane track as the rotor I5' of the motor B turns in a clockwise direction. After passing the working arcs 32', the vanes I9' are forced inwardly as they pass across the cam surface of the vane tracks intermediate connecting portions 34' that are positioned in the motors outlet areas and fluid is discharged by the inner ends of the vanes I9', this fluid passing out through the vane slot ports 28' of both of the end plates 23' and 24', through the radial passages 29 on the outer faces of said end plates and into the outlet ports 26 of both of the end plates 23' and 24'; fluid passing out through the ports 26' of the end plate 24' passes across the rotor through the spaces between the outer ends of the vanes I9', into the ports 26 of the end plate 23', thence, together with the fluid discharged by the outer ends of the vanes and the fluid that is discharged by the inner ends of the vanes I9' through the ports 26' of the end plate 24', into the discharge channel 45' and finally into the return passage or pipe 46.

Theoretically it is merely necessary that the 4 inner ends of the pumps vanes .I9 supply precisely the volume of fluid required by the inner ends of the motors vanes I9 but in commercial.

practice this is diflicult if not impossible of attainment because of variation in leakage, ts of the parts, etc., which will occur` as between individual pumps and motors even though made to the same dimensions and close tolerances. In practice therefore it is necessary that the inner ends of the pumps vanes supply fluid in excess of the volume actually required by the' inner ends of the motors vanes I9'. This may be accomplished in numerous ways, such, for example, as by making the vanes I9 of the pump A thicker than the vanes I9' of the motor B so that the inner end of each pump vane has an area greater than that of each motor vane I9'. In the present embodiment however this is accomplished by the simple method of providing the pumps rotor I5 with a greater number of vanes than are provided in the motors rotor I5'; this is clearly for the excess fluid pumped by the inner ends sliding fits with said heads.

of the pumps vanes I9 and not required by the inner ends of the motors vanes I9'. Moreover, it is necessary that the pressure of the fluid admitted to the inner ends of the vanes I9', to force them radially outward against the vane track, be greater than but correlated with the pressure of the fluid admitted to the ports 25'. The means by which both these requirements are met will now be described.

Referring to Fig. l, the passage 49 is connected with a passage 66 leading to the fluid inlet port of a differential relief or pressure reducing valve C. The outlet port of the valve C is connected to a passage 61 leading to theA passage 39. The'function of the valve C is to regulate the flow of fluid (i. e., the excess fluid not required bythe motors vanes I9') from the passage 49 to the passage 39 in such manner that the pressure of the fluid in the passage 49 exceeds by a substantially constant, predetermined amount the pressure of the fluid in the passage -39 in order to provide differential high pressure relation to the fluid supplied to the inner ends of the motors vanes I5' with respect to the pressure of the fluid supplied to the outer ends thereof. Thefvalve C may accordingly assume any suitable form of differential pressure, resistance, "re1ief or pressure reducing valvecapable of accomplishing this function. The particular structure of the valve C illustrated in Fig, 1 has been found to function reliably and satis# factorily in practice and will now be described.

The valve C includes a housing 50 provided with a valve bore in which a valve piston 55 isslidably fitted. The valve piston 55 is formed with two heads of unequal diameter, the diameter of the head 56 exceeding the diameter of the l head 51, and the valve bore-is similarly formed with two unequal diameters in order to provide 51 are separated by a neck or reduced'portion 58 having a tapered end 59 adjacent the head 56, and the neck 58 and its tapered end 59 arev of such length that one or the other of them is in'communicationr with the valves inlet port 5I isi/all positions of radjustment of the valve piston The valve piston 55 is urged toward its fully closed position, in which it is shown in Fig. 1,',by a spring 6I, one end of which is received within a recess inthe adjacent end of the valve piston 55 and the other end of which bears against a somewhat hat-shaped abutment piece 62. The

abutment piece 62 also bears against a screw 63 carried by the cover 54 and saidscrew 63 provides means by which the compression of the spring 6I may be adjusted; in the present instance the screw 63 is ofthe headless type and a pipe plug 64 closes the outer end of the enlarged opening provided for use in adjusting said screws position.

Both ends of the valve piston 55 are adapte to be acted upon by fluid having the same pressure as that in the valves outlet port 52'.l The outlet port 52 is accordingly connected wit/h the passage 65 which connects with the end of the valve bore containing the spring 6I at a point which will not be covered by the head 56 when the valve piston 55 is in its maximum open posi- The 'heads 56 and tion. A hole or passage 60 extends axially through the valve piston 55 so that both ends of the valve bore will contain uid under the same in amount to the force produced by the action of this pressure fluid upon a surface area equal to the difference in the areasof the two heads 55 and 51. Similarly the valve piston 55 is urged toward its fully closed position (or toward the left as viewed in Fig. 1) by duid-exerted force determined by the pressure oi' the fluid in the inlet port 52 and equal in amount to the action of this pressure uid upon an area equal to the difference in areas of the heads 55 and 51, and this fluid-exerted force is supplemented by the force of the spring 6I acting in the same direction.

The valve piston 55 is accordingly moved by one or the other of these opposing forces whenever they are unbalanced and will be so moved until these opposing forces are made equal to each other by change in the relative pressures in the inlet port 5I and outlet port 52 produced by movement of the valve piston 55. In this manner the valve piston 55 moves to regulate the flow of fluid from the passage 49 to the passage 39 to provide pressure in the passage 49 that exceeds the pressure in the passage 39 by an amount determined by the force exerted by the spring 6I. 'I'his relative diierence in pressures is maintained irrespective of absolute pressures; that is to say, irrespective of the actual amounts of thepressures existing in the inlet port 5| and outlet port 52 respectively and, 4within the limits of the "rate of the spring 6I', is likewise maintained substantially constant irrespective of the volume of fluid passing through the valve C. The valve piston 55 is immediately moved to its fully closed position, as shown in Fig. 1, by the spring 5| whenever the difference in pressures is less than the amount determined by said spring and in the fully closed position the head 51 completely closes the outlet port 52 thus cutting 0H all uid communication between the valves inlet port 5 I and outlet port 52.

The cover 53 is provided with a narrow flange 69 which projects into the valve bore and acts as a stop for the valve piston 55 so that substantially all of the adjacent end of the valve piston is continuously exposed to pressure fluid even when the valve is in its closed position.

The valve C thus functions: to regulate the ow of excess fluid pumped by the inner ends of the pumps vanes I9 so that diil'erential high pressure relationship is at all times maintained between the pressure of the fluid supplied t0 the inner and outerA ends of the motor vanes I 9'; that is to say, the pressure of the fluid supplied to the inner ends of the vanes I9' at all times exceeds by a substantially constant, predetermined amount the pressure of the fluid supplied to the outer ends thereof. The amount of this pressure difference may be adjusted as required by means of the screw 9| and is preferably kept at the lowest value producing satisfactory operation of the vanes I9' of the motor B. In practice it has been found that pressure differential of from ten to thirty iive or forty pounds per sq. in. is usually sumcient although differential pressures up to and including seventy-five pounds per sq. in. have been successfully employed in systems of this general character.

The present invention has numerous advantages. For example, the vane type pump supplies fluid at two different pressures, thus making it unnecessary to pass the entire output of the pump through a pressure reducing or differential pressure valve, thus increasing the efiiciency of the transmission. Moreover, when a variable capacity vane pump is employed, as in the present instance, the volume of fluid delivered at each of the two relative pressures is varied in corresponding or substantially proportional amounts so that any change in one will produce a correspondingchange inthe other, thereby assuring an ample supply of fluid at each of these two different pressures and at the same time avoiding any material excess in the volume needed at any time. In this connection it should be noted that the volume of fluid required by the inner ends of the motor vanes I9' will always bear a proportional relationship to the volume of fluid required by the outer ends of said vanes I9', and these two volumes will change proportionately with change in rotative speed of the rotor I5'. For example, to use purely arbitrary flgures in which leakage is neglected, let us assume that a fluid volume of 10 gals. per min. admitted to the outer ends of the vanes I9 causes the rotor I5' to revolve at 600 R. P. M. and that a fluid volume of 1 gal. per min. is then required motor B, will simultaneously vary the fluidvolume supplied to the inner ends of the motor vanes I9 in accordance with the requirements thereof at the changed speed of the motor.

'I'he small differences in the pressures of the fluid pumped by the inner and the outer ends of the pump vanes I9, according to the present embodiment, does not adversely ail'ect the operation of the pump A and is so small that it does not cause undue deflection or increase in Wear of the flexible interconnecting track elements 3|.

It is frequently convenient to utilize the differential high pressure at the inner ends of the vanes during the portion of their rotary movement in which the outer yends thereof are moving across Athe working arcs 32 and across the portions of the vane track on the fixed abutments 30 that separate the two fluid sections of the pump, as in the embodiment already described. While this arrangement gives satisfactory operation, it is not essential and pressure other than that of the differential high pressure fluid may be employed at the inner ends of the vanes during this part of their rotary movement. This will be understood, for example, from consideration of Fig. 4 which illustrates a modied form of end plate for the pump A.

'I'he end plate |23 of Fig. 4 corresponds generally to the endT plate 23 of Fig. 2b but is modifled to provide a pair of vane slot ports |28 which are arranged to connect with the inner ends of the vanes during only the time that the outer ends thereof are moving from the Working arcs 32 toward the fixed abutments 30, that is to say, during only the portion of their rotary movement in which they are moving radially inward. The rotor face of the end plate |23 is also formed with two pairs of recessed vane slot ports |30 and |32 respectively which are disposed intermediate the vane slot ports 21 and |28 and are adapted to connect with the inner ends of the vanes I9 during only the portion of their rotary movement in which the outer ends thereof are traversing respectively the arcs on the fixed abutments 38 which separate the two uid sections of the pump and the working arcs 32. Each of the vane slot ports |30 and |32 is connected with one of the high pressure or discharge ports 26, as by passages |3I formed on the outer face of the end plate |23 as indicated by the dotted lines in Fig. 4. The end plate |23 of Fig. 4 is otherwise the same as the end plate 23 of Fig. 2a. 'Ihe mating end plate for use with the modified end plate |23 is, of course, correspondingly modied, and uid pumped by the inner ends of the vanes passes out through suitable openings in the vane slot ports |28 of said mating end plate, these openings corresponding to the openings 22 of the end plate 24 as shown in Fig. 2b.

With this arrangement, fluid from the disports are .bothconnected with the conduit 249.

The valve C is substantially the samev as the already described valve C of Fig. l, differing therefrom only in certain particulars which will now be explained. Referring to Figs. 1 and 5 for convenience in comparison, the passage 65 of the valve C ofv Fig. 1 is omitted in the valve C' of Fig. 5; the cover member 53 of the valve C is charge or high pressure ports 26 for the outer ends of the vanes is supplied to the inner ends of the vanes during the time that the outer ends thereof are moving across the Working arcs 32 and the portions of the track surface on the xed abutments which separate the two fluid sections of the pump. The vanes I9 are thus held firmly in contact with the vane track during this portion of their rotary movement and the arrangement has' the advantage of somewhat reducing the radially outward force active to urge the vanes into contact with, the vane track at these points to separation between the high and low pressure areas of the pump with a consequent reduction in friction and wear.

The pump A may be modified in other ways.

For example, it may be modied in accordance with the arrangement diagrammatically illustrated in Fig. 5 in which the circulated fluid pumped by the inner ends of the vanes I9 may be the same as or different from the circulated iiuid pumped by the outer ends thereof and in which the pressure of the fluid pumped by the inner ends of said vanes I9 may be the same as or diierent from the pressure of the fluid pumped by their outer ends.

Referring now to Fig. 5, as schematically shown the uid supply pipe 42 is connected with the two inlet ports 25 voi" the modified end plate 223. The pair of inlet vane slot ports 21 are suitably connected with a separate fluid supply pipe 242 which may take its supply'from the same source as that of the Vsupply pipe 42 or the two supply pipes 42 and 242 may each take its supply from a separate source, as when the circulated uid to be pumped by the inner ends of the vanes I9 is to be diiferent from the circulated fluid pumped by their outer ends. It will be observed that the recessed grooves 29 (which connect the vane slot ports 21 with the inlet ports 25 in Figs. 2a

'and 2b) are omitted in the modied end plate `by a modied valve C' whose inlet and outlet provided with a passage 265 which is` suitably connected with the discharge passage 239, as byl a branch passage 261. With this modified arrangement both ends of the valve piston 55 of the valve C' are acted upon by fluid having the same pressure as that in the discharge passage 239. 'I'he valve C' of Fig. 5 functions in the same manner as the valve C of Fig. 1, so that with the arrangement illustrated in Fig. 5 the pressure of the fluid in the vane slot ports 28 and inthe portion of the passage 249 intermediate said van-e slot ports and the valve C is kept at a value exceeding by a substantially constant amount (determined by the spring 6I) the pressure of the iiuid in the passage 239 and vin the outlet izing the pressure of the uid passing to the valve C from the vane slot ports 28 with th pressure of the fluid in the passage 239.

While described and explained in connection with a vane typepump, some features of the present invention are likewise applicable to fluid pressure devices employed as vane type fluid motors. For example, modified end plates of the character illustrated in Fig. 4 may be employed in vane type uid motors, such, for example, as the motor B illustrated in Figs. 1 and 3.. The term fluid pressure device as used in the appended claims is accordingly intended to include both pumps and fluid motors..

It is to be understood that the foregoing are merely exemplifying disclosures and that changes, some of which have been indicated, may be made in the apparatus without departing from the f'invention which` is dened in the appended claims. 1

Iclaim: I

1. A rotary v ane pump having a rotor provided with a plurality of vane slots, vanes movable inward and outward in said slots in a substantially radial direction with respect to said rotor, the inner ends of said slotsv forming working chambers for the inner ends of said vanes as said vanes reciprocate therein, a casing including a pumping chamber for the outer ends of said vanes as said vanes rotate with said rotor, passages for the admission of fluid to the inner ends of said slots and to the outer ends of said vanes, and separate outlet passages for the discharge of iiuid from the outer ends of said vanes and the inner ends of said slots respectively for utilizing separately the rotary and radial movements of the vanes to deliver two fluid volumes at least in part separately usable, including means responsive to difference in the fluid pressures of said two volumes for regulating the pressure of the fluid of one of said volumes conformably with the pressure of the uid of the other of said volumes.

2. A rotary vane pump having a rotor provided with a plurality of vane slots and vanes reciprocable therein, the inner ends of said slots forming working chambers for the inner ends of said vanes as said vanes reciprocate therein, a casing including a pumping chamber for the outer ends of said vanes as they rotate with said rotor, passages for the admission of fluid to the inner and outer ends of said vanes, separate outlet passages for the discharge of fluid from the outer ends of said vanes and the inner ends of said slots respectively whereby the inner and outer ends respectively of the vanes pump separate fiuid volumes at least in part separately usable, and a fluid connection between said separate outlet passages including valve mechanism active to regulate the flow of fluid between said outlet passages to maintain the fluid in the outlet passage for the inner ends of said pump vanes at a pressure exceeding by a substantially constant amount the pressure of the fluid in the outlet passage for the outer ends of said pump vanes.

3. A rotary vane pump having a rotor provided with a plurality of vane slots and vanes reciprocable therein, the inner ends of said slots forming working chambers for the inner ends of said vanes as said vanes reciprocate therein, a

casing including a pumping chamber for the outer ends of said vanes as they rotate with said rotor, passages for the admission of fluid to the inner and outer ends of said vanes, separate outlet passages for the discharge of fluid from the outer ends of said vanes and the inner ends of said slots respectively whereby the inner and outer ends respectively of the vanes deliver two, at

least in part uncombined, fluid volumes, and a fluid connectionv between said separate outlet passages including valve mechanism active to regulate the flow of fluid between said outlet passages to maintain a substantially constant pressure differential between the pressure existing in one of said outlet passages with respect to the `pressure existing in the other of said passages.

4. A variable 'capacity rotary vane pump having a rotor provided with a plurality of vane slots and vanes movable inward and outward in said slots in a substantially radial direction with respect to said rotor, the inner ends of said slots forming working chambers for the inner ends of said vanes as said vanes reciprocate therein, a casing including a pumping chamber for the outer ends of said vanes as said vanes rotate with said rotor, passages for admission of fluid to the inner ends of said slots to the outer ends of said vanes, separate outlet passages without free and constantly open fluid connection therebetween for the discharge of fluid from` the outer ends of'said vanes and the inner ends of said slots respectively, whereby the rotary and radial movements of the vanes are utilized separately to pump separate fluidvolumes to pump two fluid-volumes which are at least in lpart separately usable, means for simultaneously varying the volumes of fluid pumped by the inner ends and the outer ends of said vanes and means for maintaining the fluid pressure of one of said volumes equal to or greater than the fluid pressure of the other of said volumes.

V5. A rotary vane pump having a rotor provided with a plurality of vane slots and vanes movable inward and outward in said slots in a substantially radial direction with respect to said rotor, the inner ends of said slots forming working chambers for the inner ends of said vanes as equal to the pressure existing in the other.

6. A rotary vane pump having a rotor provided with a plurality of vane slots and vanes movable inward and outward in said slots in a substantially radial direction -with respect to said rotor, the inner ends of said slots forming working chambers for the inner ends of said vanes as said vanes reciprocate therein, a casing including -a pumping chamber for the outer ends of said vanes as said vanes rotate with said rotor, a first port for admitting a fluid supply vto the outer ends of said vanes, a second Dort for admitting a fiuid supply to the inner ends of said slots and arranged to connect therewith while the outer ends of the vanes therein are moving in connection with said first named port, a third port for the discharge of fluid by the outer ends of said vanes, a fourth port for the discharge of fluid from the inner ends of said slots and arranged to connect with the inner ends of said slots while the outer ends of the vanes therein are moving in connection with said third named port, separate discharge passages for said third and vanes as said vanes move inwardly and outwardly, a vane track for guiding the vanes in their in and out movement and provided adjacent the rotor with a chamber disposed between high and low pressure areas on the opposite circumferential sides thereof, the outer ends of said vanes being subject to the respective pressures in said chamber and in said areaswhile passing therethrough, a low pressure port arranged to connect with the inner endsof said slots while the outer ends of the vanes therein are passing through the low pressure area, a high pressure port arranged to connect with the inner ends 4of said slots while the outer ends of the vanes therein are passing through said high pressure area, a third port disposed intermediate said high and low pressure ports and arranged to connect with the inner ends of the slots during only the time that the outer ends of the vanes therein are moving through said chamber, means for maintaining in said high pressure port a pressuregreater than but correlated with the pressure in said high pressure area and means for maintaining in said third port a pressure substantially equal to the pressure in said high pressure area.

8. In a rotary vane type fluid pressure device, a rotor having a plurality of vanes movable inwardly and outwardly thereof in slots formed aecomo 9 therein, the inner ends of said slots comprising working chambers for the inner ends of said vanes as said vanes move inwardly and outwardly, a high pressure port and a low pressure port arranged to connect successively with the outer ends oi the vanes as they rotate in unison with the rotor, a working chamber for the outer ends of said vanes disposed circumferentially intermediate said high and low pressure ports, and v l means for supplying uid from said high pressure port to the inner ends of the slots during only the portion of their rotary movement in which the outer ends of the vanes therein are moving intermediate said high and low pressure ports, means for substantially equalizing the pressure in the inner ends of said slots with the pressure in said low pressure port during the time that the leading and trailing faces of the corresponding vanes are connected with said low pressure port and means for maintaining in the inner ends of said slots uid pressure related to lbut greater than the pressure in said high pressure port during the time that the leading and trailing faces of the corresponding vanes are connected with said high pressure port.

9.'In a rotary vane type pump, a rotor having a plurality of slots, vanes in said slots movable inwardly and outwardly in a substantially radial direction, the inner ends of said slots comprising working chambers for the inner ends of said vanes as said vanes move inwardly and outward- 1y, a. pumping chamber for the outer ends of said vanes, separate passages for the admission of uid to the outer ends of said vanes and the inner ends of the slots respectively, separate passages without free and constantly open fluid connection therebetween for the discharge of fluid from the outer ends of said vanes and the inner ends of said slots respectively, whereby the rotary and radial movements of the vanes are utilized separately to supply separate volumes of pressure iluid that are at least in part separately usuable and means for maintaining the iiuid pressure of one of said volumes equal to or greater than the fluid pressure of the other of said volumes.

10. The combination of a rotary piston-carrying element having radially movable pistons,

Aseparate pumping chambers for the outer and inner ends respectively of said pistons, means for causing the inner and outer ends of said pistons to pump separate fluid volumes without free and constantly open fluid connection therebetween and means responsive to the iiuid pressures of both of said volumes for regulating the pressure of the lluid of one of said volumes conformably with the pressure of the liuid of the other of said volumes.

11. The combination of a rotary piston-carrying element having pistons rotatable therewith and reciprocable with respect thereto, means utilizing separately the rotary and reciprocating movements respectively of the pistons to pump two uid volumes without free-and constantly open fluid connection therebetween and valve means responsive to the fluid pressures of both of said volumes for regulating the pressure of the fluid of one of said volumes conformably with the'pressure of the fluid of the other of said volumes.

12. In a rotary vane type fluid pressure device, a rotor having a plurality of slots, vanes in said slots movable inward and outward with respect to said rotor, said slots comprising working chambers ior said vanes as said vanes move inwardly and outwardly, a working chamber for said vanes as said vanes rotate with said rotor, means utilizingseparately the rotary and the inward-andoutward movements respectively ol the vanes for the circulation of two separate uncombined fluid volumes without iluid connection therebetween and means responsive to the uid pressuresof both of said volumes for maintaining the fluid pressure of one of said volumes equal to or greater than the fluid pressure of the other of said volumes.

`13. In a rotary vane type pump, a rotor having a plurality of slots, vanes in said slots movable inward and outward with respect to saidrotor, said slots comprising working chambers for said vanes as said vanes move inwardly and outwardly, a working chamber for said vanes as said vanes rotate with said rotor, means utilizing separately the rotary and the inward-and-outward movements respectively of the vanes topump two fluid volumes that are at least in part separately usable and means responsive to difference in fluid pressures of said volumes and active to maintain the iluid pressure of one of said volumes equal to or greater than the fluid pressure of the other of said volumes. l

14. In a rotary vane type pump, a. rotor having a plurality of slots, vanes in said slots movable inwardly and outwardly with respect to the rotor, the inner ends of said slots forming working chambers for the inner ends of said vanes as said vanes move inwardly and outwardly, a casing including a working chamber for the outer ends of said vanes, means for admitting fluid to the inner ends of said slots and to the outer ends of said vanes, separate outlet circuits without uid connection therebetween for said chamber and for ,the inner ends of said slots respectively, whereby the outer and inner ends respectively of said the liuld pressure of one of said volumes equal to or greater than the fluid pressure of the other of said volumes. l

15. In a variable `capacity rotary vane type pump, a rotor having a plurality of slots, vanes in said slots movable inwardly and outwardly with respect to the rotor, the inner ends of said slots forming working chambers for the inner ends oi said vanes as said vanes move inwardly and outwardly, a casing including a working chamber for the outer ends of said vanes, means for admitting fluid to the inner ends of said slots and to the outer ends of said vanes, separate outlet circuits without iluid connection therebetween for said chamber and for the inner ends or said slots respectively, whereby the outer an dinner ends respectively of said vanes pump two wholly separate uncombined uid volumes, means for sipumped by the outer and the inner ends respectively of said vanes, and means responsive to the pressures of both of said volumes for maintaining the fluid pressure of one of said volumes equal to or greater than the fluid pressure of the other oi said volumes.

cnARLEs M. KENDRICK. 

